BENGALURU: The year 2020 will be etched in the minds of people as the Covid-19 pandemic, which began in December 2019, brought entire mankind to its knees. The Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) was initially characterized by predominantly respiratory involvement. As the pandemic began to unfold, it was recognised that the virus not just affected the lungs, but even the heart, blood, brain, kidneys, liver etc. This multi-system involvement by a predominantly ‘respiratory virus’ left the medical fraternity puzzled. Then began a flurry of questions regarding the nature of virus, pathogenesis, diagnosis and treatment. Many are unanswered even after a year.
Even more puzzling was that the virus affected the length and breadth of the nervous system, including the brain, spinal cord and peripheral nerves. The neurological involvement was seen not only during the Covid infection but also several months later (Post Covid). We can call it ‘Covid Neurology’.
One third of patients who required hospitalisation have altered consciousness of varying degrees. The nervous system involvement is independent of respiratory involvement. The brain (encephalopathic) features were more common in the elderly, with involvement of other parts of the nervous system more common in the younger age group. The virus enters the brain via blood (hematogenous) or through the nose (olfactory) route. The Angiotensin converting enzyme receptors on the endothelial cells of blood vessels in the brain could be the potential entry point.
The most commonly noted neurological manifestations are headache, malaise, loss of smell and taste, and convulsions. The following case histories are illustrative of the varied presentations of Covid-19 neurological syndromes.Kamala (name changed), aged around 45, with novel coronavirus infection -- fever, sore throat, flu-like symptoms and loss of taste and smell -- presented to the emergency ward with sudden onset of left-sided weakness with slurred speech on day three of fever. She underwent RT-PCR test and was found positive. She had comorbidities factors like diabetes, hypertension or cardiac issues, or risk factors for stroke, and was treated with anti-platelet medications and advised physiotherapy. This suggests that Covid infection can spread to brain and cause stroke-like manifestation.
In the second case, Gopal (name changed), aged 28, had severe respiratory infection and required ventilatory support, and was hospitalised for nearly three weeks but slowly recovered. Three weeks later, he returned with complaints of difficulty in getting up from squatting position and walking, with tingling sensation in lower limbs and upper limbs. He was diagnosed to have post-Covid Guillian-Barre (GB) syndrome, required re-admission and was treated with intravenous immune-globulins (IVIg) for five days. He recovered slowly and could walk with support. This is definitely suggestive of post-Covid neurological involvement.
The third case was of an elderly gentleman John (name changed), aged 65, who had Covid respiratory infection, requiring hospitalisation, but recovered within two weeks. One month later, he presented with altered alertness, hallucination, impaired cognition and double incontinence. His brain MRI showed demyelination involving temporal lobe, and autoimmune encephalitis. He was treated with steroids and IVIg and partially recovered cognition at the time of discharge.
The first case was probably caused by Covid-19 coagulopathy, the second case demonstrated involvement of peripheral nerves due to auto-immunity and third was CNS demyelination, secondary to post-Covid infection. The neurological manifestations can occur during or following a mild or severe Covid infection and involve different parts of the neuraxis. The exact prevalence of such involvement is yet to emerge as most of the published literature is anecdotal, and the neurological spectrum is yet to unfold completely.